"Thomas T. Veldhouse" wrote in message
.. .
Scott W wrote:
You are missing the big reason, 1 color / pixel for raw vs. 3 colors /
pixel for tiff.


True ... but there are Red, Green and Blue pixels, each getting 12-bits of
linear data, which makes up one pixel [three colors] in TIFF. In fact,
for
some reason, I believe Bayer sensors have two green pixels for every RGB
pixel
in TIFF.


But the fact is, in a so-called "6 megapixel" camera,
there are only 6 million sensors, distributed between
Red, Green and Blue. Green gets 2X as many pixels
as either Red or Blue, so in this example, 1.5 million
(each) of Red and Blue, and 3 million green.

In the equivalent TIF file there will be 18 million
values (6 million per color.)

Each reading (in the sensor) may be up to 12 bits,
but the lossless compression will reduce the overall
storage by 20-30%. Thenet result for a RAW file
is roughly one byte per pixel.

It's the RAW converter program that does the
interpolation from RAW to TIF, and that's where
the file size gets tripled.


rafe b
www.terrapinphoto.com